1. Field of the Invention
This invention relates to a bicycle hub assembly, more particularly to an improved bicycle hub assembly which has a relatively long service life.
2. Description of the Related Art
Referring to FIG. 1, a conventional bicycle hub assembly 10 includes a hollow hub body 11 having two enlarged end portions 112. Two ball bearings 12 are mounted respectively in the enlarged end portions 112. Each of the ball bearings 12 has an inner ring 121, an outer ring 122 and balls (113a) confined between the inner and outer rings 121, 122. The outer ring 122 is in tight contact with the hub body 11. An elongated shaft 13 passes rotatably through the hub body 11 and is fixed to the inner ring 121 of each of the ball bearings 12. The elongated shaft 13 has two ends 131 extending outwardly of the hub body 11. An annular hub cover 14 is sleeved fixedly around the elongated shaft 13 adjacent to each of the enlarged end portions 112. The hub cover 14 has an inner end (14a), which contacts one of the ball bearings 12 and an outer periphery 113 of one of the enlarged end portions 112, and an outer end (14b) opposite to the inner end (14a). Since the hub cover 14 is press-fitted non-removably to the elongated shaft 13, the entire hub assembly has to be replaced even though only a ball bearing is worn out. This is not economical.
FIG. 2 shows installation of the hub assembly 10 to a fork 30. The hub assembly 10 is mounted to the fork 30 by means of a mounting unit 20. A left prong portion 31 of the fork 30 is pressed against the outer end (14b) of one hub cover 14 by means of a nut member 21 of the mounting unit 20, and a right prong portion 32 of the fork 30 is pressed against the outer end (14b) of another hub cover 14 by means of a press member 22 of the mounting unit 20. Referring also to FIG. 1, the pressure force applied on the hub cover 14 causes the hub cover 14 to abut against the adjacent ball bearing 12 and the outer periphery 113 of the hub body 11 in a relatively tight manner. Thus, the friction between the inner end (14a) and the outer periphery 113 of the hub body 11 is relatively large when the bicycle rotates, thereby countering rotation of the bicycle's wheel and wearing the hub cover 14 easily. Accordingly, the conventional hub assembly 10 cannot have a long service life.